Sam noticed how Dean smiled at Lexi as she told him she had both had worse company and been worse company than Dean. He knew lexi had the ability to make anyone smile, no matter the situation but seeing her bring Dean's smile out felt like he had just witnessed a miracle happen. He also saw how Dean caught what the shadow of Lexi's engagement ring and his smile lowered ever so slightly, knowing it would be a heavy reminder of the fact the two of them were very much in the same stage of life, even if Lexi had been in it longer than Dean had, and managed to pull herself out of the darkest part of that tunnel. 

He wasn't in the slightest bit surprised that Dean chose to mock him utterly childishly with a scrunching up of his nose and snarling it in the process. He wasn't going to retort with anything but it seemed Lexi's idea of continuing to get any extra ideas for what it was they were hunting whilst Dean showed her to the armoury distracted Dean. 

Lexi looked between the brothers as Sam agreed to the plan and Dean muttered and stammered his reply. "i'll be at the table in the war room when you're ready" Sam replied to Lexi. Any other time, he probably would have told Dean to behave himself, considering the mischievous smile didn't escape his notice, but it was still a raw time so he didn't want to push his luck. 

"Perfect! Lead the way when you're ready. The sooner we get back out there, the better I'll feel about it." Lexi smiled back at Dean. "Consider it your thanks for the food" she quipped at Dean, giving her own mischievous smile back at him as she stood up frm her chair at the table, then pushing it back under the table after herself. Sam got up also and headed to the war room and back to the table. 

"Please be able to help each other" he muttered to himself about the two of them. He wanted to see them both happy again as he knew they deserved it. He hated seeing his brother in full grief, even though he knew it was more than reasonable and it was their way. Yet he also hated seeing Lexi have her moments of bad nights as well, he might not have known her for a long time, not like how he and Dean had known Mika for, but he had grown to really like Lexi and trust her with his life on hunts.